The present invention relates in general to ultrasound apparatus for medical diagnostic imaging, and more specifically to measurement and display of differential backscatter cross section per unit volume of insonified tissue.
Acoustic parameters useful in medical ultrasound include reflection at discontinuities, volume backscatter coefficient, absorption coefficient and Doppler frequency shift. Ultrasonic measurement of these parameters provides a basis for various tissue characterizations and for constructing images. Although reflection imaging (using extrinsic measurements) has historically been the principal basis for diagnostic ultrasound, it is realized that intrinsic parameters are useful for tissue localization and characterization and for detection of pathology.
Backscatter coefficient has been investigated for its utility in imaging and characterization and has been found to provide diagnostically useful quantitative data. However, tissue pathology is not alwasy readily apparent from absolute measurements of the backscatter coefficient. For example, it is sometimes required to perform filtering of broadband backscatter data to find frequency dependencies of the backscatter coefficient to identify pathological tissue.
The success of a diagnostic modality in providing useful information depends on an ability to interrogate tissue and acquire acoustic data with a maximum signal-to-noise ratio (SNR). However, specular reflections, signal correlations, inhomogeneous attenuation, and other factors result in a generally low SNR in ultrasound backscatter measurement.
Accordingly, it is a principal object of the present invention to provide a method and apparatus for collecting quantitative backscatter data.
It is another object to improve tissue characterization and diagnosis by means of quantitative backscatter data.
It is another object to improve the signal-to-noise ratio in measurements of intrinsic acoustic parameters for ultrasound.
It is still another object of the invention to detect localized variations in backscatter intensity and dependencies in an object.